Here are some examples:
Function equation:
1.
y = a*x^2 + b*x + c
2.
y = log(2,x)
Parametric equation:
x = a*sin(t); y = b*cos(t)
Polar equation:
r = a*cos(b*t + pi/2)
You can select equations from the equation gallery that contains some predefined equations.
You can save the equations for later use.